Attachment system for prosthesis

ABSTRACT

An attachment system secures a residual limb to an artificial limb in a comfortable and substantially non-rotational manner. The attachment system offers proximal anchoring of the residual limb in a hard socket, by connecting a side surface of a residual limb liner to the side surface of the socket. Preferably, this connection is accomplished using an extension member extending from the liner through a portion of the socket interior, through the socket wall, and attaching to a latch mechanism. The preferred attachment system requires no clearance in the bottom of the socket well because neither the extension member nor the latch mechanism is located between the distal end of the residual limb/liner and the bottom of the well. The attachment system is preferably disposed entirely along the side of the limb and the side of the socket.

This application is a continuation of, and claims priority of, U.S.patent application Ser. No. 10/746,208, filed Dec. 23, 2003, entitledAttachment System For Prosthesis, issuing as U.S. Pat. No. 7,077,868 onJul. 18, 2006, which is a continuation-in-part of U.S. Non-Provisionalpatent application Ser. No. 09/972,729, filed on Oct. 4, 2001, entitled“Attachment System for Prosthesis,” issued on Dec. 23, 2003 as U.S. Pat.No. 6,666,894, which claims priority of U.S. Provisional PatentApplication Ser. No. 60/238,301, filed on Oct. 4, 2000, entitled“Attachment System for Prosthesis,” wherein the above applications areincorporated herein by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to prosthetics, and, morespecifically to an attachment system used in the donning/doffing of asocket onto a residual limb. The present invention more particularlyrelates to an attachment system that requires little or no clearanceinside the socket between the socket and the residual limb, thatcontrols rotation of the prosthesis, and that may be used with asuction-fit socket system. The invented attachment system extends fromthe side of a liner on the user's limb, through an aperture in thesocket, to the outer side of the socket, substantially proximal on thelimb and on the socket relative to conventional more “distal” attachmentdevices. Therefore, the invented attachment may properly be called anexterior, proximal attachment device for a prosthesis.

2. Related Art

For years, many different methods have been used to retain or “suspend”a prosthetic limb on an amputee's residual limb. Gravitational and otherforces, for example, from movement of the limbs, tend to causeseparation between the prosthetic limb and the patient's residual limbduring use. This happens, for example, during the swing phase of gait,when a prosthetic leg is additionally subjected to centrifugal forces.Patients have routinely worn a variety of belts, straps, cuffs, andharnesses to retain their prosthetic limbs against separation from thelimb during these periods. However, such devices are often inconvenientand may tend to cause chafing against the patient's body, giving rise tosores and abrasions.

The manner in which an artificial limb is suspended and/or attached tothe residual limb determines the amount of control an amputee has overthe prosthesis. Therefore, by improving suspension/attachment withoutadding weight and excessive mechanism, the amputee may obtain improvedcomfort, convenience, and suspension mobility.

A common approach to tackling this problem has led to the design of aroll-on suction liner, which is rolled onto the residual limb andattached at its distal end to a socket or artificial limb. The liner,which is usually fabricated from silicone, or some other gel form, fitssnugly over the residual limb, preferably completely covering the distalend of the residual limb and extending for at least several inches tocover the entire circumference of the proximal region of the residuallimb. The liner, in turn, is enveloped, especially at its distal end, bythe socket of the prosthesis, which is also called a “hard socket.” Asuction fit is preferably formed between the hard socket and the liner.This suspension method is very advantageous for the amputee. It givesthe amputee the ability to better control the prosthesis and providesfor useful sensory or proprioceptive feedback. Suction suspension alsomakes a prosthesis feel lighter, compared to other forms of suspension.Unfortunately, only a small percentage of amputees can successfully andcomfortably wear a liner without another form of suspension. Therefore,the socket liner is typically equipped with a detachable component, atits distal end, which mates with a locking device in the interior of thesocket at the bottom of the interior space or “well.” This systemsecures the distal end of the residual limb/liner to the distal end ofthe artificial limb socket well, and, hence, is called a “distalattachment.” The locking device in the distal end of the socket welltypically employs a spring-loaded clutch mechanism or a pin-lockmechanism. The component on the distal end of the liner is typically acylindrical barb-shaped structure or frictionally-retained pin.

One problem associated with such designs is the tugging or pull on thedistal end of the limb. Most of these locks are not air tight, thusallowing air to flow into the hard socket and to eliminate the“suction.” When this happens, the only suspension is the pin, which is atraction suspension, rather than suction. In cases where prostheticsocks are worn outside the liner, there is a risk the user's limb willbecome trapped in the socket if the sock is caught in the lockingdevice. In these incidents, most patients are forced to make emergencytrips to their practitioner to remove the prosthetic. Also, the lockingdevice and attachment component cooperate in such a way to permit thebarb or pin to lock in a plurality of longitudinal positions, whichaffects the overall length of the prosthesis. This can make it difficultfor the patient to consistently achieve the same prostheticconfiguration when the residual limb and the artificial limb arearticulated. It should be further noted that, by weight of the lockbeing added at the distal end of the residual limb or near the distalend of the socket, this can make the prosthetic device feel heavierbecause of a “lever arm” effect, than if the same weight were placedmore proximally. Additionally, many amputees, whether because of thelength of their residual limb or their height, do not have room in thesuction liner-socket-prosthesis combination for a distal lockingmechanism. Or, additionally, use of a distal lock may limit what otherprosthetic components that patient may use.

Despite the large number of suspension options available, none of theabove-mentioned devices act to eliminate rotation between the hardsocket and the suction liner. In an attempt to alleviate the rotationproblem, a design called a “quad socket” has been used for many years.The quad socket is shaped in a square manner more than a cylindricalmanner, and forcing the “cylindrical” limb to fit tightly in this squarereceptacle makes the prosthesis less apt to rotate on the limb, much asif you made a wheel square. Unfortunately, this is not a verycomfortable position for the limb. Today, there has been a trend towardmore naturally-shaped sockets, making rotation control even moredifficult.

Therefore, there is still a need for an improved attachment system forprosthetics. Also, there is a need for improving retention of the stumpin the socket without sacrificing the patient's comfort and withoutcomprising on expense, weight and simplicity of use of the prosthesis.There also is a need for improving rotation control, which will improvethe patient's overall comfort and agility.

SUMMARY OF THE INVENTION

The present invention is an attachment system and methods for connectinga prosthesis to a residual limb of the user. Preferably, the attachmentsystem extends from the side surface of a liner on a residual limb tothe outside side surface of a hard socket fitted around the liner andlimb. Preferably, the attachment system includes a strap system thatconnects to the outer side surface of the liner to the socket, whereinsaid strap extends into the socket along a portion the limb, and throughan aperture in the sidewall of the socket. Preferably, the strap furtherextends to a buckle or other latch mechanism connected to the outer sidesurface of the socket, typically about midway or more, proximally, onthe outside surface of the socket. The externally mounted buckle iseasily reached and maintained by the user, and easily retrofit as anadd-on feature to existing hard sockets. In this way, a combination ofthe invented prosthetic attachment system and suction fit providesuperior retention of the artificial limb on the user.

The preferred strap system includes a disk member or “umbrella” that maybe adhesively secured to the surface of the liner, and an elongatedstrap that extends distally from the umbrella and longitudinally a shortdistance along the side surface of the limb. The strap may be secured tothe umbrella in such a way that its exact angle relative to the limb'slongitudinal axis may be adjusted as desired and then locked in place,for example, by tightening of a bolt. The lock is preferably abuckle-style latch mechanism, with a spring-biased member and one ormore sharp edges, that frictionally engage transverse detents locatedbetween transverse raised ridges on the strap's surface. Thus, the strapis inserted into the buckle to the extent desired by the user, and, in aratchet-like action, the sharp edges wedge into the transverse detentsand secure the strap from being pulled out or away from the buckle.Thus, the strap is anchored in the buckle, and the socket is heldclosely on the residual limb until the user chooses to unbuckle thebuckle.

The especially preferred embodiment includes a duel strap and bucklesystem wherein one strap and one buckle are located on the medialsurface of the liner and socket respectively and one strap and onebuckle are located on the lateral surface of the liner and socketrespectively. The especially preferred embodiment also includes theinvented strap and buckle system wherein said strap may have a “nipple”shaped tab extension at its most distal end to facilitate the strapthrough the buckle. Also, the underside of the said strap may have asmall grooved channel at its distal end in order to feed the strap overa rivet in the base of the buckle. The especially preferred buckle mayinclude a spring-biased member with one or more sharp edges, thatfrictionally engage transverse detents located between transverse raisedridges on the strap's surface. In order to remove said strap from saidbuckle, the user pulls the distal end of the buckle away from thesocket.

Therefore, the prosthetic attachment system is easily accessible,effective, simple, and easy to use. The versatility and simplicity, andnon-interfering design of the invented prosthetic attachment systemhelps provide reliable and comfortable suspension for an artificial limbon a great number of persons with limb deficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a close-up, lateral view one embodiment of the prostheticattachment system according to the invention, installed on a user'sresidual limb.

FIG. 2 is a lateral view of the preferred prosthetic attachment systemshowing the strap as it enters the inside of the socket.

FIG. 3 is a lateral view of the preferred prosthetic attachment systemshowing the strap after it has entered the socket and as it passesthrough an opening in the socket to the socket's outer surface.

FIG. 4 is a lateral view of the preferred prosthetic attachment systemshowing the strap after it has entered the buckle.

FIG. 5 is a lateral view of the preferred embodiment after theprosthetic is installed on the user's residual limb, showing the foot.

FIG. 6 is a side view of one embodiment of the buckle-style latchmechanism of the present invention.

FIG. 7 is a top view of the lever of the buckle of FIG. 6.

FIG. 8 is a top view of the buckle of FIG. 6.

FIG. 9 is a frontal view of the base frame of the buckle of FIGS. 6 and8.

FIG. 10 is a side view of one embodiment of the lever of the buckle ofFIGS. 6 and 8.

FIG. 11 is a frontal view of the pin of the buckle of FIGS. 6-10.

FIG. 12A is a plan view of one embodiment of an umbrella plate forattachment to an outside surface of a liner.

FIG. 12B is a side view of one embodiment of a strap according to theinvention, for cooperating with, and connecting, the buckle-style lockand the umbrella plate.

FIG. 13 is a ventral view of the especially preferred embodiment of theprosthetic attachment system showing two straps located laterally andmedially.

FIG. 14 is a close-up, lateral view of the especially preferredembodiment of the prosthetic attachment system of FIG. 13.

FIGS. 15-17 are sequential, lateral views of the especially preferredembodiment of the prosthetic attachment system of FIGS. 13 and 14depicting the process of installing a prosthetic on a residual limb.

FIG. 18 is a detail side view of the strap of FIGS. 13-17 in relation tothe buckle of FIGS. 13-17, before the strap is inserted in the buckle.

FIG. 18A is a detail side view of the strap of FIGS. 13-18 in relationto the buckle of FIGS. 13-18, after the strap is inserted in the buckle.

FIG. 19 is a top view of the especially preferred embodiment of thestrap of FIGS. 13-18.

FIG. 20 is a bottom view of the especially preferred embodiment of thestrap FIGS. 13-19.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, there is shown one preferred embodiment andthe especially preferred embodiment, but not all embodiments, of thepresent invention, which is referred to herein as an attachment system.In this Description and the Claims, the term “proximal” means toward thecenter/torso of the body, and so toward the top/upper end of the linerand prosthetic device. Thus, in the case of a prosthetic device for aperson's leg, “proximal” would mean nearer or toward the upper thigh andtrunk. “Distal” means away from the center/torso of the body, and so theregions of the liner or prosthetic device farther out from the trunk,farther out on the leg.

The preferred buckle 26 or latch mechanism of the invented attachmentsystem includes base 10, which is mounted on the external surface of thehard socket 12 by means of a rivet 20, glue or other fastener, or it mayeven be molded integrally with the socket 12. The buckle 26 ispositioned proximally higher up the socket than conventional “distal”locks that are mounted near the distal end of the socket, typically atthe bottom of the inside “well” of the hard socket 12. Connected to base10 are a lever 11 and pin 11′ with e-clips 11″, which together create abiased system for receiving and capturing strap 22, as seen in FIGS. 8and 12B. Strap 22 , as discussed below, is preferably secured to theliner 16, by means of a umbrella 18 (see FIG. 12A), and is long enoughto comfortably and conveniently extend from the middle to upper regionof the side of the liner to reach the lower region of the liner (seeFIG. 2).

Liner 16 may be a custom or a pre-manufactured liner as described in theRelated Art section above. Examples of currently-available conventionalliners are ICEROSS, ALPHA, LUXURY LINER, ALPS, SILIPOS (all trademarks).Modern urethane liners are especially preferred.

Strap 22 is connected at its proximal end to liner 16, preferably by anumbrella 18 or other fixture or bracket. The umbrella 18 may be glued tothe liner, as seen in FIG. 2. Umbrella 18, as shown in FIG. 12A, ispreferably an aluminum plate structure of approximately ¾″ in diameterand ¼″ thick, with preferably a slightly-concave inner surface forcontacting the glue, and with apertures at various locations on theumbrella to assist in receiving and better gripping of the glue thatconnects the umbrella 18 to the liner's 16 outside side surface.However, umbrella 18 may also be sewn onto or into liner 16, or it maybe formed integrally with liner 16. Also, alternatively, other shapes ofan attachment plate or other attachment means may be used instead of theumbrella, as long as preferably they are thin and easily slide/fit intothe socket.

The strap 22 is attached to the umbrella 18, for example, with a10/24-spanner bolt or screw. The screw is then tightened down to theumbrella 18, rather than allowing the strap 22 to pivot around thescrew. This results in the strap 22 being adjustable, allowing the useror prosthetist to move the strap 22 and then lock it into the optimumposition, even if the strap 22 or lock mechanism have been attached totheir respective structures in less-than-perfect position or location.

When hard socket 12 is installed on the residual limb, it extends upover and around liner 16 and umbrella 18, as shown in FIG. 1. Strap 22extends from umbrella 18 on liner 16 a short distance on the inside ofsocket 12 through an aperture 15 in socket 12 to the external surface ofsocket 12 (see FIGS. 2 and 3). There, the strap 22 continues to extendto and through the preferred buckle 26 attached on the outside surfaceof the socket 12, as shown in FIG. 4. The buckle 26 adjustably receivesthe distal end of the strap 22, by means of the strap 22 extendingthrough the buckle 26 between the base 10 and the lever 11. The strap 22is pushed/pulled through the buckle 26 to the point where the hardsocket 12 is securely, but comfortably secured around and connected toliner 16 via the strap 22 and umbrella 18 combination. This way, theadvantages of the invention are realized.

Strap 22 is preferably sufficiently rigid, sufficiently long, and ispositioned so that, upon the limb/liner being inserted into the socket,the strap naturally tends to slide to and through the aperture15, to thebuckle 26, and through the buckle 26 with little or no need for the userto thread or pull the strap 22 through the aperture 15 or buckle 26. Aprosthetist will be able to adjust the strap and/or buckle locations andaperture size to enable this smooth movement and latching of the strapin the buckle. Optionally, the socket wall surface, on the interior orexterior, may be contoured to facilitate and direct the strap.

The release button of the buckle 26 is buckle lever 11, which featuressharp edge 13, as shown in FIG. 7. The top surface of base 10 ramps upin thickness in the distal direction. This provides for easier strap 22entry into the buckle-style latch mechanism, and increasing pressure onthe strap 22 when engaged by means of the buckle lever 11pressing/ratcheting against the strap 22. Edge 13 engages the sharp“ratchet teeth” of strap 22, extending into the transverse detents 17and abutting against the teeth walls upending from the strap top surface(see FIG. 12B). Any pull on the strap 22 in the proximal direction isresisted by the engagement of edge 13 in detents 17 and the pressure oflever 11 against e-clips 11″. The attachment system may be placed in aposition on the liner and socket that the prosthetist deems mostadvantageous and convenient for the patient. The mechanism is attachedto the exterior of the socket at a location determined by test socketfitting, but in any event, not at the distal end of the socket.Typically, when a single attachment system is employed, it will placedin a lateral position so that the user may reach it by reaching towardthe outside of his limb.

After mounting of the base 10 of the buckle 26 onto the socket 12, theumbrella 18 onto the liner 16, and strap onto the umbrella 18, theroll-on prosthetic liner 16 of choice is applied to the patient. Thepatient can then step into the hard socket 12 and engage the attachmentsystem, by inserting the strap 22 through the aperture 15 and into thebuckle 26. This procedure may be used in the retrofitting of theattachment system to an existing prosthetic.

If a new prosthetic is being created, the liner 16 is applied to thepatient, and the ideal location for the umbrella 18 is marked on liner16. A mold over the patient's limb and liner 16 is then taken. After themold and liner 16 are removed, the umbrella 18 is then attached to theliner 16 in the location marked. From the mold the hard socket 12 iscreated, and the base 10 of the lock mechanism is attached in the properlocation on the outside of hard socket 12, and then the aperture 15 iscreated in hard socket 12 as above.

The aperture 15 or any other opening through the socket preferably maybe easily sealed by a gel suction wrap/cover, or other air-tight wrap orplug that preferably encases the lock mechanism and aperture. Thisallows and maintains a “suction” fit between the socket and the linerthat improves the function of the prosthetic.

EXAMPLE

The above attachment system was fit to three test patients. All three ofthese patients utilized ALPHA™ liners in a normal manner. The lockingtab was attached to the ALPHA™ liners in a normal manner. Two of thesepatients were unilateral transtibial amputees, and one patient was aunilateral congenital above-knee amputee. The above-knee amputee was acongenital amputation resulting from PFFD, and his amputation level wasconsistent with a knee disarticulation level. All three of thesepatients either demonstrated problems with conventional distal pin-locksystems, or, in the case of the transfemoral amputee, did not havesufficient room to install any of the distal locking mechanismscurrently on the market. These patients were using the prosthetic locksuspension according to the present invention on their prosthesis on adaily basis. These patients were all experimentally fit in June of 2000and no problems were encountered with mechanical failures or withpatient acceptance or satisfaction. We continue to monitor thesepatients at 2-3 week intervals.

One may see, after reviewing the disclosure of this Description and theDrawings, that the invented attachment system tends to prevent rotationof the prosthesis on its longitudinal axis (axis extending between itsproximal end and distal end) relative to the amputated limb. Byproviding one of the invented side-located, “proximally-located”attachment systems, such rotation is limited or prevented. This isbecause strap extends from a fixed anchor location on the side of theliner/limb to a fixed anchor location on the side of the socket, thusconnecting those two fixed locations together at substantially a fixeddistance apart, thereby not allowing the anchor location on the socketto rotate any significant distance away from the anchor location on theliner. Although one of the invented attachment systems is preferred,more than one may possibly be used, for example, at two positions aroundthe side of the limb/socket, as described below in the EspeciallyPreferred Embodiment section.

Other benefits of the attachment system include comfort and ease of use.The preferred attachment system is simple to use, each to reach, andrequires a minimum of dexterity. The externally-mounted lock mechanismeliminates the jamming of conventional distal locks often caused by asock worn over the roll-on liner.

While a ratchet-style buckle and strap combination is preferred, otherreleasable attachments and fasteners may be used. For example, extensionmembers other than a flat strap with detents may be used, such as acord(s), loop(s), tab(s), or other rigid or flexible extension members.Latch mechanisms other than a buckle may be used, such as a hook(s),clip(s), snap(s), or other devices that adjustably or non-adjustablygrip the extension member. The connection between the extension memberand the latch mechanism is preferably, but not necessarily, adjustable.This permits the user or the prosthetist to manipulate the connectionfor optimum use and comfort, either by lengthening or shortening theconnection or by pivoting or otherwise moving the location of theextension member or latch mechanism.

AN ESPECIALLY PREFERRED EMBODIMENT

In the Description and Claims, the term “lateral” means on/toward theouter surface or region of the body, and therefore, on/toward the outersurface or region of the apparatus that is installed on the human body.Thus, a lateral surface of the liner or socket is an outer side surface,away from the inner or medial plane of the body. See lateral surfaces101, 101′ of the liner and socket, respectively, in FIGS. 13 and 14,wherein the apparatus is on the left leg and FIG. 13 is a ventral(front) view. The term “medial” means on/toward the inside or medialplane of the body. Thus, a medial surface of the liner or socket is aninner side surface, away from the outside of the body. See medialsurfaces 102, 102′ of the liner and the socket, respectively, in FIG.13, wherein the apparatus is on the left leg.

The especially preferred embodiment comprises one or more attachmentsystems having improved straps and latch mechanisms that make donningand doffing the prosthesis more convenient and comfortable. Theembodiment of FIGS. 13-17 comprises two straps 122, one attached to thelateral surface 101 of the liner 16 and one attached to the medialsurface 102 of the liner 16, as shown in FIG. 13. These two straps aresecured to the liner by means of an umbrella 18 described above andshown in FIGS. 1-12B.

The especially preferred strap 122 has a “nipple” shaped tab extension114, or other tapered, narrow tip, at its distal end. The extension 114preferably has a width less than half of the width of the strap122. Theextension facilitates the strap122 from the inside of the socket 12 tothe socket's external surface and through the buckle 126 (see FIG. 19).The bottom surface 123 of the especially preferred strap 122 may have alongitudinal channel 124, or other grove or ramp-like shape at thedistal end, to prevent the strap 122 from “catching” on the rivet 20 inthe base 110 of the buckle 126. The thinness (from top surface to bottomsurface) of the central region of the distal end, caused by the channel124, aids in smooth insertion of the strap 122 into the buckle 126, andallows the distal end to slide over the rivet 20. This way, the rivet 20need not be lowered or countersunk into the base 110. Alternatively, theentire bottom surface of the distal end of the strap may beslanted/thinned, but this would result in a weaker distal end.

In order to install the socket 12 on the residual limb, the user placesthe two straps 122 inside the socket 12 and then feeds them through twoapertures 115 located medially and laterally in the socket's 12 sidewall, as seen in FIGS. 15 and 16. Once the tabs 114 of the straps 122exit the apertures 115 to the external surface of the socket 12, theyfeed into two buckles 126, distal from the apertures 115, on the medialand lateral surface of the socket 12 (see FIGS. 16 and 17). Theespecially preferred buckle 126 may include a spring-biased member withone or more sharp edges 113, that frictionally engage transverse detents17 located between transverse raised ridges on the strap's surface.Connected to each base 110 of the buckles 126, are a lever 111, pivotaxle pin 111′, and e-clips 111″ or other biasing spring or member, whichtogether create a biased system for receiving and capturing the straps122. The top surface of each base 110 ramps up towards the distal end ofthe buckle 126, allowing easy insertion of the straps 122, as shown inFIG. 18. As the distal end of each strap 122 moves into the proximal endof each buckle 126, the sharp edge or edges 113 of the buckles 126engage the transverse detents 17 of the straps 122 (see FIG. 19). Thechannel 124, on each strap 122, bypasses the rivet 20 in base 110 of itsrespective buckle 126, allowing the distal end strap 122 to exit thedistal end of the buckle 126, in turn securing the socket 12 to theresidual limb (see FIG. 19).

The especially preferred method for releasing the straps 122 from thebuckles 126, is for the user to pull up on the distal end of each lever111 to pivot the lever 111 into a raised position as shown in FIG. 18A,which corresponds to pivoting the distal end of the lever 111 away fromthe socket. This, in turn, disengages the sharp edge or edges 113 ofeach buckle 126 from the transverse detents 17 of each strap 122 (seeFIGS. 18 and 19). The user is then able to remove the socket 12 from theresidual limb by holding on to each lever 111 and pulling the socket 12off the liner and also by maneuvering his/her residual limb out of thesocket. Having a plurality of attachment systems for a single prostheticdevice may improve stability and comfort for the user. By utilizinglateral and medial strap and buckle combinations, rotation of theprosthetic device relative to the user's residual limb is minimized, ifnot prevented. Further, the levers of the lateral and medial bucklesprovide a hand-hold for the user, especially during removal of thesocket from the liner-covered residual limb. The lift-to-release bucketlevers may be easier to operate and may provide a better hand-grip forthe user, compared to the embodiment of FIGS. 1-12B which requires thatthe user push and hold down the levers of the buckles during removal ofthe prosthesis.

While lateral and medial positions for two strap and buckle combinationsare preferred, other locations and other numbers of strap and bucklecombinations are also possible. The buckles in FIG. 13 are depicted tobe quite large and to protrude significantly from the socket, thebuckles may be made to be small and low-profile, so that the strap andbuckle combination is discreet when covered by clothing and comfortablefor walking without the buckle catching on the other leg or clothing.Preferred levers 11 and 111 are deemed to be convenient and reliable forlatching and unlatching their respective buckles, and preferably, eachlever is biased into the latched position and requires positive actionby the user or prosthetist to unlatch it. However, other styles of latchmechanisms may be used, such as other pivotal arms or hooks, snaps,clips, or other releasable locks and latches.

Preferably, the prosthesis attachment system comprises the inventedextension member and latch system, with or without the aid of suctionbetween the liner and the socket, but no other straps or attachments.Preferably, there is no belt or strap extending to encircle part of theuser's body, and preferably no attachment between the distal end of thelimb/liner and the bottom of the well of the socket.

Although this invention has been described above with reference toparticular means, materials and embodiments, it is to be understood thatthe invention is not limited to these disclosed particulars, but extendsinstead to all equivalents within the broad scope of this disclosure andthe following claims.

1. An attachment system for a prosthesis comprising: a prosthesis havinga socket with a side wall surrounding and defining an interior well forreceiving a user's residual limb, the socket having a proximal end, adistal end, a midway location halfway between said proximal end and saiddistal end, and a longitudinal dimension between said proximal end andsaid distal end; a roll-on liner adapted to attach to a user's residuallimb by surrounding the residual limb, the roll-on liner being receivedin the socket; an extension member passing from the roll-on linerthrough an aperture in the socket side wall between the proximal end andthe midway location and connecting to a lock that is outside the socketbetween the proximal end and said midway location.
 2. An attachmentsystem according to claim 1, comprising a plurality of said extensionmembers spaced at various radial positions around the liner.
 3. Anattachment system according to claim 1, wherein said roll-on liner has adistal end and a proximal region, and wherein the extension member isattached to said proximal region.
 4. An attachment system according toclaim 3, comprising a plurality of said extension members spaced atvarious radial positions around the liner, wherein at least one of saidextension members is located at a lateral position on said proximalregion and at least one of said extension members is located at a medialposition on said proximal region.
 5. An attachment system according toclaim 1, wherein said lock is a latch mechanism on said outer sidesurface of the socket, and wherein said extension member has a proximalend attached to a proximal region of said roll-on liner and a distal endreleaseably locked in said latch mechanism.
 6. An attachment system asin claim 1, wherein said lock comprises a pivotal arm and a bias member,and the extension member further comprises a strap having transverseteeth in its upper surface and detents between said teeth, wherein thestrap slides through the lock and is retained in the lock by the pivotalarm being biased into said detents.
 7. An attachment system as in claim6, wherein said pivotal arm has a pivot axis and extends distally fromsaid pivot axis and is adapted to be pivoted away from said socket torelease the strap from the lock
 8. An attachment system as in claim 1,wherein the extension member further comprises a strap with alongitudinal axis, a width transverse to the longitudinal axis, and anextension at a distal end of the strap, the extension having a widththat is less than half of the width of the strap.
 9. An attachmentsystem as in claim 8, wherein said extension has a longitudinal channelwith a ramped bottom wall.
 10. An attachment system for a prosthesis,comprising: a liner adapted to fit over the residual limb of a user,said liner having a proximal region and a distal end, and an outsidesurface adapted to extend circumferentially all the way around theresidual limb; a strap secured to the proximal region of said liner'soutside surface, said strap extending towards the distal end of saidliner; a socket for fitting over said liner and said residual limb, saidsocket having a proximal end and a distal end, a midway location halfway between the proximal end and the distal end, an inside surface, andan outside surface; an aperture in said socket for allowing said strapto pass from the inside surface of the socket to the outside surface ofthe socket, said aperture being placed between the proximal end and saidmidway location on said socket; and a lock mechanism on the outsidesurface of said socket for receiving and securing said strap.
 11. Anattachment system according to claim 10 wherein said strap has aplurality of transverse detents on the top surface thereof.
 12. Anattachment system according to claim 11 wherein said lock mechanismcomprises a buckle device with a spring-biased lever with a sharp edgefor engaging one of said transverse detents.
 13. An attachment systemaccording to claim 10 wherein said lock mechanism comprises anunlatching mechanism operable at a distal end of the lock mechanism. 14.An attachment system according to claim 10, wherein said lock mechanismcomprises a ratchet buckle with a lever at its distal end, the leverbeing pivotal into a latch position near the socket wherein it securesthe strap in the lock mechanism, and pivotal into an unlatch positionaway from the socket wherein it release the strap to slide out of thelock mechanism.
 15. An attachment system according to claim 10comprising two of said straps and two of said latch mechanisms, whereinone strap and one cooperating latch mechanism are located laterally onthe liner and socket, and wherein one strap and one latch mechanism arelocated medially on the liner and the socket.
 16. An attachment systemfor a prosthesis, comprising: a liner adapted to fit over the residuallimb of a user, said liner having a proximal region and a distal end,and an outside surface adapted to extend circumferentially all the wayaround the residual limb; a socket for fitting over said liner and saidresidual limb, said socket having an interior well defined by asidewall, and a socket proximal rend, a socket distal end, and a socketmidway location half way between said proximal end and said distal end;a strap secured to said the proximal region of the liner, said strapextending towards the distal end of said liner and into said interiorwell; a lock mechanism on said sidewall between said midway location andsaid proximal end of the socket for receiving and securing said strap,so that the prosthesis is suspended from the liner by the strap.
 17. Theattachment system of claim 16, wherein the liner is adapted to create asuction suspension with the socket sidewall.